Many expired COVID-19 tests can still be used, but it depends on the specific brand and lot number. The FDA extended the shelf life of numerous at-home test kits beyond their original printed expiration dates, meaning the date on your box may no longer be accurate. Before you toss that test or rely on it for a result, you need to check whether your specific kit received an extension.
How to Check if Your Test Has an Extended Date
Start by finding the lot number on your test kit’s box. It’s typically printed near the expiration date on the outer packaging. Once you have it, go to the FDA’s page for at-home COVID-19 diagnostic tests, where a searchable table lists every authorized test along with any updated expiration dates. Look up your test’s brand name and lot number. If your lot appears with a new date that’s still in the future, the test is considered valid regardless of what’s printed on the box.
If your lot number doesn’t appear in the FDA’s table, the expiration date was not extended, and the test should be thrown away. It’s also worth noting that the FDA is no longer extending expiration dates for newly manufactured test kits, so this applies mainly to tests distributed during the pandemic’s peak years.
A few brands never received extensions at all. QuickVue At-Home, On/Go One Antigen, and AccessBio CareStart tests should be judged solely by the printed date on the box. If that date has passed, discard them.
What Happens to a Test After It Expires
At-home COVID tests work by using chemical reagents on a small strip to detect viral proteins in your nasal sample. Over time, those reagents degrade. The nitrocellulose membrane inside the test strip absorbs moisture and changes properties, and the antibodies that bind to the virus lose their reactivity. Heat accelerates this process significantly. Most test kits are designed to be stored between 36°F and 86°F. Research has found that storage at around 99°F for just three weeks can impair a test’s sensitivity, and temperatures of 113°F over two months cause measurable damage to the internal membrane. If your test sat in a hot car, a garage, or a mailbox during summer, it may have degraded faster than the expiration date accounts for.
Cold storage has its own risks. Temperatures near freezing (36 to 39°F) for even a few days have been shown to impair the accuracy of some lateral flow tests, potentially producing false results.
Expired Tests Can Miss Low-Level Infections
A study published in Microbiology Spectrum tested 100 expired BinaxNOW kits against unexpired ones using known concentrations of virus. At higher viral loads, the expired tests still produced positive results. But at lower concentrations, the differences became important. Both the control and sample lines were noticeably fainter on expired kits. With low-concentration virus samples, the positive line on expired tests was barely visible, even though it appeared consistently across all 100 tests.
This matters in real life. Early in an infection, or toward the tail end, your viral load may be low. An expired test is more likely to show a faint, ambiguous line or miss the infection entirely during those windows. If you’re testing because of mild symptoms or a known exposure and the result is negative, an expired test gives you less confidence than a current one would. A strong positive on an expired test, on the other hand, is still meaningful.
The Control Line Isn’t a Guarantee
Some guidance, including from the California Department of Public Health, suggests that an expired test may still be usable if the control line appears clearly visible and matches the color described in the instructions. The control line confirms the test’s liquid flowed properly across the strip, which is a basic functionality check. However, the research on expired BinaxNOW kits found that even when the control line appeared, it was fainter than on fresh tests. A working control line tells you the test ran, but it doesn’t tell you the reagents are sensitive enough to catch a low-level infection. Think of it as a minimum threshold, not a seal of approval.
When an Expired Test Is Worth Using
If you’re symptomatic and it’s the only test you have, using an expired test (that still falls within an FDA-extended date) is reasonable. A positive result on an expired test is reliable. The concern is with negatives: they carry more uncertainty than they would with a fresh kit. If you get a negative on an expired test but still feel sick, testing again with a newer kit in 24 to 48 hours is the practical move.
If your test is past both the printed and any extended expiration date, the result becomes much less trustworthy in either direction. At that point, it’s better to get a new test. The federal government’s free COVID test program through USPS is no longer accepting new orders as of March 2025, so purchasing tests at a pharmacy or through a retailer is currently the main option. Many insurance plans still cover the cost.
How to Store Tests You Have Now
If you’re stocking tests for future use, keep them indoors at room temperature, out of direct sunlight, and away from moisture. A bedroom closet or kitchen cabinet works fine. Avoid storing them in bathrooms (humidity), cars (heat extremes), garages, or anywhere temperatures swing outside the 36 to 86°F range. Proper storage is the single biggest factor, beyond the calendar date, in whether your test will still work when you need it.